蓝牙应用程序连接故障

Question

在设备上进行连接时出现问题，该应用程序应创建附近可用设备的列表，在单击所需设备上时，将建立连接，我想在以后发送数据，但是当我单击在所选设备上，该应用程序崩溃了，我已尽力而为，但无济于事，请提供帮助

enter code here
package com.example.arduinobluetoothinterface;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

import java.io.IOException;
import java.util.ArrayList;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {
    public static final int REQUEST_ENABLE_BT = 1;
    public static final UUID my_uuid = UUID.fromString("0000110E-0000-1000-8000-00805F9B34FB");
    private static final String TAG = "Main app";
    final BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    public BroadcastReceiver BlueToothReceiver;
    public BluetoothSocket mBluetoothSocket;
    public BluetoothDevice mBluetoothDevice;

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // Don't forget to unregister the ACTION_FOUND receiver.
        unregisterReceiver(BlueToothReceiver);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Creating Array List
        final ArrayList<BtDevicesClass> listOfNames = new ArrayList<BtDevicesClass>();
        //Creating Array Adapter Object
        final ArrayAdapterBt bluetoothArrayAdapter = new ArrayAdapterBt(this,
                listOfNames);
        //Setting bluetooth
        if (mBluetoothAdapter != null) {
            //if bluetooth is supported and Turn it on and make the device discoverable
            if (!mBluetoothAdapter.isEnabled()) {
                //making an Intent to enable bluetooth
                Intent newIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                //start the intent
                startActivityForResult(newIntent, REQUEST_ENABLE_BT);
                //making an intent too set the device discoverable
                Intent newIntent2 = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
                //start the intent
                startActivityForResult(newIntent2, 2);
            }
        } else {
            message("Bluetooth is not supported on this Device");
        }
        /*
        when a button is clicked the app will start searching for nearby bluetooth devices
        and when he finds them he will list them int list View
         */
        Button searchButton = findViewById(R.id.search_button);
        searchButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //start searching for nearby devices
                mBluetoothAdapter.startDiscovery();
                message("Searching For Nearby Devices");
                mBluetoothAdapter.startDiscovery();
                IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
                registerReceiver(BlueToothReceiver, filter);
            }
        });
        // Create a BroadcastReceiver for ACTION_FOUND.
        BlueToothReceiver = new BroadcastReceiver() {
            public void onReceive(Context context, Intent intent) {
                //Creating listView Object
                final ListView listOfDevices = findViewById(R.id.list_of_objects);
                //Setting Array Adapter
                listOfDevices.setAdapter(bluetoothArrayAdapter);
                String action = intent.getAction();
                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    // Discovery has found a device. Get the BluetoothDevice
                    // object and its info from the Intent.
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice
                            .EXTRA_DEVICE);
                    String deviceName = device.getName();
                    String deviceHardwareAddress = device.getAddress(); // MAC address
                    listOfNames.add(new BtDevicesClass(deviceName, deviceHardwareAddress));
                    message(deviceName);
                            /*
                            handle clicking on list element to connect to it
                             */
                    listOfDevices.setOnItemClickListener(new AdapterView
                            .OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> parent, View view,
                                                int position, long id) {
                            mBluetoothAdapter.cancelDiscovery();

                            BluetoothSocket temp = null;
                            try {
                                temp = mBluetoothDevice.
                                        createRfcommSocketToServiceRecord(my_uuid);
                            } catch (IOException e) {
                                message("error while creating bluetooth path");
                                e.printStackTrace();
                            }
                            mBluetoothSocket = temp;
                            try {
                                mBluetoothSocket.connect();
                            } catch (IOException e) {
                                e.printStackTrace();
                                message("Can't establish a Connection ");
                            }

                        }
                    });
                }
            }
        };
    }

    private void message(String msg) {
        Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
    }
}

这是错误跟踪

D / AndroidRuntime：关闭VM E / AndroidRuntime：致命异常：main     进程：com.example.arduinobluetoothinterface，PID：17512     java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“ android.bluetooth.BluetoothSocket android.bluetooth.BluetoothDevice.createRfcommSocketToServiceRecord（java.util.UUID）”         在com.example.arduinobluetoothinterface.MainActivity $ 2 $ 1.onItemClick（MainActivity.java:109）         在android.widget.AdapterView.performItemClick（AdapterView.java:310）         在android.widget.AbsListView.performItemClick（AbsListView.java:1194）         在android.widget.AbsListView $ PerformClick.run（AbsListView.java:3240）         在android.widget.AbsListView.onTouchUp（AbsListView.java:4202）         在android.widget.HwAbsListView.onTouchUp（HwAbsListView.java:434）         在android.widget.AbsListView.onTouchEvent（AbsListView.java:3904）         在android.view.View.dispatchTouchEvent（View.java:8601）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2513）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2157）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在android.view.ViewGroup.dispatchTransformedTouchEvent（ViewGroup.java:2519）         在android.view.ViewGroup.dispatchTouchEvent（ViewGroup.java:2171）         在com.android.internal.policy.impl.PhoneWindow $ DecorView.superDispatchTouchEvent（PhoneWindow.java:2491）         在com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent（PhoneWindow.java:1804）         在android.app.Activity.dispatchTouchEvent（Activity.java:2827）         在android.support.v7.view.WindowCallbackWrapper.dispatchTouchEvent（WindowCallbackWrapper.java:69）         在com.android.internal.policy.impl.PhoneWindow $ DecorView.dispatchTouchEvent（PhoneWindow.java:2452）         在android.view.View.dispatchPointerEvent（View.java:8807）         在android.view.ViewRootImpl $ ViewPostImeInputStage.processPointerEvent（ViewRootImpl.java:4662）         在android.view.ViewRootImpl $ ViewPostImeInputStage.onProcess（ViewRootImpl.java:4520）         在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:4034）         在android.view.ViewRootImpl $ InputStage.onDeliverToNext（ViewRootImpl.java:4087）         在android.view.ViewRootImpl $ InputStage.forward（ViewRootImpl.java:4053）         在android.view.ViewRootImpl $ AsyncInputStage.forward（ViewRootImpl.java:4190）         在android.view.ViewRootImpl $ InputStage.apply（ViewRootImpl.java:4061）         在android.view.ViewRootImpl $ AsyncInputStage.apply（ViewRootImpl.java:4247）         在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:4034）         在android.view.ViewRootImpl $ InputStage.onDeliverToNext（ViewRootImpl.java:4087）         在android.view.ViewRootImpl $ InputStage.forward（ViewRootImpl.java:4053）         在android.view.ViewRootImpl $ InputStage.apply（ViewRootImpl.java:4061）         在android.view.ViewRootImpl $ InputStage.deliver（ViewRootImpl.java:4034）         在android.view.ViewRootImpl.deliverInputEvent（ViewRootImpl.java:6463）         在android.view.ViewRootImpl.doProcessInputEvents（ViewRootImpl.java:6437）         在android.view.ViewRootImpl.enqueueInputEvent（ViewRootImpl.java:6390）         在android.view.ViewRootImpl $ WindowInputEventReceiver.onInputEvent（ViewRootImpl.java:6622）         在android.view.InputEventReceiver.dispatchInputEvent（InputEventReceiver.java:185）         在android.os.MessageQueue.nativePollOnce（本地方法）         在android.os.MessageQueue.next（MessageQueue.java:148）         在android.os.Looper.loop（Looper.java:151）         在android.app.ActivityThread.main（ActivityThread.java:5668）         在java.lang.reflect.Method.invoke（本地M I / Process：正在发送信号。 PID：17512 SIG：9 应用已终止。